Electric heating pads, electric blankets, electric throws, and other localized fabric material heating devices are well known. Such devices commonly employ a heating area, generally in the form of a fabric member which is associated with one or more heating elements generally positioned interior of a multi-layer fabric member and safety and control circuitry which may include temperature setting selectively actuatable controls coupled to temperature sensors in the area of the elements. Such devices may be provided for different voltages. It has also been known to provide heated seats in automobiles and other vehicles where the heating coils are positioned under the seat surface and where the actuating controls include both on/off switches, temperature sensors preventing overheating and, in some instances, circuitry which deactivates either upon the attaining of a predetermined temperature or upon the expiration of a set time period. It has also been known to interface such seats with the vehicles ignition system so that the seat heating is disabled when the ignition is turned off. While such heated seats in vehicles have proven utility in cold weather regions, they are generally expensive, not retrofittable into existing vehicles, and limited in that they provide heat only to the surface area of the seat itself and therefore generally do not provide heat to occupant's legs or frontal regions.
It has long been common to provide blankets, throws and other passive warming devices for use in vehicles, however the adoption and use of electric heating for such is limited for considerations of safety, versatility and battery overuse.
Generally, electric outlets provided for use in vehicles, including more recently in aircraft, consist of low voltage sockets, generally of the type previously known as cigar lighter sockets, which often are independent of the ignition switch and continue to provide a power source, even when the engine is not running. Electric utilizing devices plugged into such sockets, if left on after the engine and its associated generator or alternator have been turned off, can rapidly drain the vehicle's battery.
In those instances where the power socket, however, has been integrated into association with the ignition, power is not available when the ignition is off, although during such periods there may be a desire to power various electronic devices. A normal expedient is to provide for an accessories position of the ignition system that does continue to provide power to the sockets as well as other areas of the vehicle. However, in the event of a relatively high drain power use device, such as would be provided by an electric warmer, long term use of such devices with the ignition in the accessory position can lead to excessive battery drain.